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ChIP sonication using a cup horn - (Sep/06/2005 )

I have problems sonicating chromatin for ChIP (foaming issues, DNA does not get small enough). I am using a Branson 450 with a microtip. I decided to try a cup horn (101-147-048) as it has been recommended (on this forum and by misonix) for sonicating chromatin for ChIP.
branson cup horns

I have never used a cup horn before and I was wandering if anyone could give me some tips on how to use these.

- what tubes should I use : eppendorf or 15mL Falcon ?
- how close should the tubes be to the surface of the horn ? (within a half-inch but without touching it...)
- Misonix states that the shearing may be more efficient if the tubes can be placed at a 30-45 angle... true?

I guess I will have to optimize the other sonication parameters such as amplitude (power), time, volume, etc.

Any help would be greatly appreciated. Thanks!



I may have the answer to all your problems! This is a mail that must draw all your attention... laugh.gif

Diagenode is proposing a truly innovative system of sonication called Bioruptor which is perfectly adapted for a number of applications in molecular and cellular biology where an optimal reproducibility is of major concern.

With the Bioruptor, it is now possible to sonicate samples in sealed tubes (Eppendorf or Falcon 15 or 50ml), without introducing a probe into the sample as traditional sonication methods require. This enables the avoidance of tedious manipulations but also the prevention of any contamination between the samples.

The Bioruptor is perfectly adapted for the ChIP assay where optimal fractionation of DNA is required. Up to 12 tubes can be sonicated in parallel and 200 to 500 bp DNA fragments are obtained in minutes (minimal sonication volume: 5 microliters).

The system is widely used in key reference labs for ChIP assay in Japan, Europe and now in North America.

We would be very pleased to propose you a two-week trial of the system in your laboratory, in order for you to test the Bioruptor perfectly.

More information can be accessed via our web page at the following address:

Looking forward to hearing from you soon.

Sincerely yours,

Simon Thiry